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OrmesbyJohn wrote:
> I'm sure its a simple piece of kit but what do I need to be able to link one
> set of speakers with two adjacent pc soundcards?
> Thanks
>
>
Many options, the cheapest and simplest being:
Use a plug-plug lead between the "speaker out" on one and the "line
in" on the other. The "other" then has to be running but can mix the
sounds from both systems and present them to the speakers.

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"Palindrome" <> wrote in message
news:c58nai$2pg0q0$-berlin.de...
> OrmesbyJohn wrote:
>
> > I'm sure its a simple piece of kit but what do I need to be able to link
one
> > set of speakers with two adjacent pc soundcards?
> > Thanks
> >
> >
> Many options, the cheapest and simplest being:
> Use a plug-plug lead between the "speaker out" on one and the "line
> in" on the other. The "other" then has to be running but can mix the
> sounds from both systems and present them to the speakers.
------------
Thanks, but wish to be able to use the speakers with either pc when the
other is either running or shut down.

On Sat, 10 Apr 2004 14:34:36 +0100, "OrmesbyJohn"
<> wrote:
>
>"Palindrome" <> wrote in message
>news:c58nai$2pg0q0$-berlin.de...
>> OrmesbyJohn wrote:
>>
>> > I'm sure its a simple piece of kit but what do I need to be able to link
>one
>> > set of speakers with two adjacent pc soundcards?
>> > Thanks
>> >
>> >
>> Many options, the cheapest and simplest being:
>> Use a plug-plug lead between the "speaker out" on one and the "line
>> in" on the other. The "other" then has to be running but can mix the
>> sounds from both systems and present them to the speakers.
>------------
>Thanks, but wish to be able to use the speakers with either pc when the
>other is either running or shut down.

Altec Lansing has some with dual inputs that work just fine with two
devices.

OrmesbyJohn wrote:
> "Palindrome" <> wrote in message
> news:c58nai$2pg0q0$-berlin.de...
>
>>OrmesbyJohn wrote:
>>
>>
>>>I'm sure its a simple piece of kit but what do I need to be able to link
>
> one
>
>>>set of speakers with two adjacent pc soundcards?
>>>Thanks
>>>
>>>
>>
>>Many options, the cheapest and simplest being:
>> Use a plug-plug lead between the "speaker out" on one and the "line
>>in" on the other. The "other" then has to be running but can mix the
>>sounds from both systems and present them to the speakers.
>
> ------------
> Thanks, but wish to be able to use the speakers with either pc when the
> other is either running or shut down.
>
> As I said, many options, you really need to provide more info if you
want a focused reply.
Two more options:

You can get switch boxes that will do the job. You will probably have to
convert the stereo jack plugs to either phono or larger jackplugs. Plan
on about 15GBP.
(But if you don't want to have to manually switch, the above won't do)

You can also get small mixing "desks" for about 20GBP. But they will
need a mains adaptor (another 5GBP). This will give you a mix of the two
signals so that you can hear both at the same time.
(But if you don't want to use something that needs a mains socket, this
won't do).

If your looking for a 2-way switch, this Co. has all different types
with the right size plugs. Also extra cables available if neededhttp://electronicsusa.com/
"Palindrome" <> wrote in message
news:c58tos$2qp2j1$-berlin.de...
> OrmesbyJohn wrote:
>
> > "Palindrome" <> wrote in message
> > news:c58nai$2pg0q0$-berlin.de...
> >
> >>OrmesbyJohn wrote:
> >>
> >>
> >>>I'm sure its a simple piece of kit but what do I need to be able to
link
> >
> > one
> >
> >>>set of speakers with two adjacent pc soundcards?
> >>>Thanks
> >>>
> >>>
> >>
> >>Many options, the cheapest and simplest being:
> >> Use a plug-plug lead between the "speaker out" on one and the
"line
> >>in" on the other. The "other" then has to be running but can mix the
> >>sounds from both systems and present them to the speakers.
> >
> > ------------
> > Thanks, but wish to be able to use the speakers with either pc when
the
> > other is either running or shut down.
> >
> > As I said, many options, you really need to provide more info if you
> want a focused reply.
> Two more options:
>
> You can get switch boxes that will do the job. You will probably have
to
> convert the stereo jack plugs to either phono or larger jackplugs.
Plan
> on about 15GBP.
> (But if you don't want to have to manually switch, the above won't do)
>
> You can also get small mixing "desks" for about 20GBP. But they will
> need a mains adaptor (another 5GBP). This will give you a mix of the
two
> signals so that you can hear both at the same time.
> (But if you don't want to use something that needs a mains socket,
this
> won't do).

"Gimpy" <> wrote in message
news:...
> If your looking for a 2-way switch, this Co. has all different types
> with the right size plugs. Also extra cables available if needed
> http://electronicsusa.com/
> "Palindrome" <> wrote in message
> news:c58tos$2qp2j1$-berlin.de...
> > OrmesbyJohn wrote:
> >
> > > "Palindrome" <> wrote in message
> > > news:c58nai$2pg0q0$-berlin.de...
> > >
> > >>OrmesbyJohn wrote:
> > >>
> > >>
> > >>>I'm sure its a simple piece of kit but what do I need to be able to
> link
> > >
> > > one
> > >
> > >>>set of speakers with two adjacent pc soundcards?
> > >>>Thanks
> > >>>
> > >>>
> > >>
> > >>Many options, the cheapest and simplest being:
> > >> Use a plug-plug lead between the "speaker out" on one and the
> "line
> > >>in" on the other. The "other" then has to be running but can mix the
> > >>sounds from both systems and present them to the speakers.
> > >
> > > ------------
> > > Thanks, but wish to be able to use the speakers with either pc when
> the
> > > other is either running or shut down.
> > >
> > > As I said, many options, you really need to provide more info if you
> > want a focused reply.
> > Two more options:
> >
> > You can get switch boxes that will do the job. You will probably have
> to
> > convert the stereo jack plugs to either phono or larger jackplugs.
> Plan
> > on about 15GBP.
> > (But if you don't want to have to manually switch, the above won't do)
> >
> > You can also get small mixing "desks" for about 20GBP. But they will
> > need a mains adaptor (another 5GBP). This will give you a mix of the
> two
> > signals so that you can hear both at the same time.
> > (But if you don't want to use something that needs a mains socket,
> this
> > won't do).
------------------------
TVM for all the advice.

Millimeter wrote:
> On Sat, 10 Apr 2004 12:50:59 +0100, "OrmesbyJohn"
> <> wrote:
>
>
>>I'm sure its a simple piece of kit but what do I need to be able to link one
>>set of speakers with two adjacent pc soundcards?
>>Thanks
>>
>
>
> How about a simple Y adapter allowing 2 in ->1 out?
> They are both output jacks on the soundcard so there will be no load
> to contend with.
>
> Just a thought,
> Millimeter

A good idea but only if you include current limiting resistors
(~100-1Kohm) in each of the Y arms (both arms so that the two channels
keep roughly the same signal levels). The outputs from sound cards are
not open collector and the output devices will be taken out of their
safe operating area when one card attempt to pull the output high whilst
the other attempts to pull it low. You can happily parallel two inputs
but not two outputs, unless they are current sink, open collector type.

"Palindrâ~»me" <> wrote in message
news:c59sg0$2qtnc2$-berlin.de...
> Millimeter wrote:
>
> > On Sat, 10 Apr 2004 12:50:59 +0100, "OrmesbyJohn"
> > <> wrote:
> >
> >
> >>I'm sure its a simple piece of kit but what do I need to be able to link
one
> >>set of speakers with two adjacent pc soundcards?
> >>Thanks
> >>
> >
> >
> > How about a simple Y adapter allowing 2 in ->1 out?
> > They are both output jacks on the soundcard so there will be no load
> > to contend with.
> >
> > Just a thought,
> > Millimeter
>
> A good idea but only if you include current limiting resistors
> (~100-1Kohm) in each of the Y arms (both arms so that the two channels
> keep roughly the same signal levels). The outputs from sound cards are
> not open collector and the output devices will be taken out of their
> safe operating area when one card attempt to pull the output high whilst
> the other attempts to pull it low. You can happily parallel two inputs
> but not two outputs, unless they are current sink, open collector type.
>

Do the resistors go in series in the signal wire? Or are they a cross from
signal to ground? Just wondering...

Toolman Tim wrote:
> "PalindrÃ¢~Â»me" <> wrote in message
> news:c59sg0$2qtnc2$-berlin.de...
>
>>Millimeter wrote:
>>
>>
>>>On Sat, 10 Apr 2004 12:50:59 +0100, "OrmesbyJohn"
>>><> wrote:
>>>
>>>
>>>
>>>>I'm sure its a simple piece of kit but what do I need to be able to link
>
> one
>
>>>>set of speakers with two adjacent pc soundcards?
>>>>Thanks
>>>>
>>>
>>>
>>>How about a simple Y adapter allowing 2 in ->1 out?
>>>They are both output jacks on the soundcard so there will be no load
>>>to contend with.
>>>
>>>Just a thought,
>>>Millimeter
>>
>>A good idea but only if you include current limiting resistors
>>(~100-1Kohm) in each of the Y arms (both arms so that the two channels
>>keep roughly the same signal levels). The outputs from sound cards are
>>not open collector and the output devices will be taken out of their
>>safe operating area when one card attempt to pull the output high whilst
>>the other attempts to pull it low. You can happily parallel two inputs
>>but not two outputs, unless they are current sink, open collector type.
>>
>
>
> Do the resistors go in series in the signal wire? Or are they a cross from
> signal to ground? Just wondering...
>
>
Series to limit the current. From signal to ground is for impedance
matching - typically if the preceding and/or following circuits use
passive filtering (which have component values calculated by including
the source and sink impedances). If they aren't correct then the filters
won't work the way intended.

"Palindr?me" <> wrote in message
news:c59tci$2pqk2j$-berlin.de...
> Toolman Tim wrote:
>
> > "Palindrâ~»me" <> wrote in message
> > news:c59sg0$2qtnc2$-berlin.de...
> >
> >>Millimeter wrote:
> >>
> >>
> >>>On Sat, 10 Apr 2004 12:50:59 +0100, "OrmesbyJohn"
> >>><> wrote:
> >>>
> >>>
> >>>
> >>>>I'm sure its a simple piece of kit but what do I need to be able to
link
> >
> > one
> >
> >>>>set of speakers with two adjacent pc soundcards?
> >>>>Thanks
> >>>>
> >>>
> >>>
> >>>How about a simple Y adapter allowing 2 in ->1 out?
> >>>They are both output jacks on the soundcard so there will be no load
> >>>to contend with.
> >>>
> >>>Just a thought,
> >>>Millimeter
> >>
> >>A good idea but only if you include current limiting resistors
> >>(~100-1Kohm) in each of the Y arms (both arms so that the two channels
> >>keep roughly the same signal levels). The outputs from sound cards are
> >>not open collector and the output devices will be taken out of their
> >>safe operating area when one card attempt to pull the output high whilst
> >>the other attempts to pull it low. You can happily parallel two inputs
> >>but not two outputs, unless they are current sink, open collector type.
> >>
> >
> >
> > Do the resistors go in series in the signal wire? Or are they a cross
from
> > signal to ground? Just wondering...
> >
> >
> Series to limit the current. From signal to ground is for impedance
> matching - typically if the preceding and/or following circuits use
> passive filtering (which have component values calculated by including
> the source and sink impedances). If they aren't correct then the filters
> won't work the way intended.

Thanks for the reminder...I dropped out of electronics repair class way back
when the VCR was a new (totally unaffordable) concept, and the Z80 was a
"state of the art" microprocessor <g>

Just in case you are NOT a troll - I'll answer your stupid question before I continue to
flame your incredible stupidity! No - I'll just save time and answer your stupid question
WHILE continuing to flame your incredible stupidity...

The back of your sound cards have plug in jacks - probably mini stereo plug jacks don't
they? Your speakers also have little mini stereo plugs that actually plug into these
jacks don't they? A normal human being with even minimal brain activity would quickly
realize that a couple of $.50 Y connectors from radio shack would soon solve his
problem...
Of course, if you are the standard moron that owns a computer these days, I would advise
you to do all this fiddling around while the computer was powered on and playing sounds
very loudly! Hoping beyond hope that you would be standing in a puddle of salt water
while doing so, with one hand on the hot water pipe.... (just covering all the bases
here)

"Kanda' Jalen Eirsie" <> wrote in message
news:...
> Greetings...
>
> On Sat, 10 Apr 2004 12:50:59 +0100, "OrmesbyJohn"
<> wrote:
>
> >I'm sure its a simple piece of kit but what do I need to be able to link
one
> >set of speakers with two adjacent pc soundcards?
> >Thanks
> >
>
>
> Oh MY GOD!!!!
>
> Apparently they no longer teach simple problem solving anymore in
liberal schools....
>
> How the hell did you ever find Usenet!???
>
> Just in case you are NOT a troll - I'll answer your stupid question
before I continue to
> flame your incredible stupidity! No - I'll just save time and answer your
stupid question
> WHILE continuing to flame your incredible stupidity...
>
>
> The back of your sound cards have plug in jacks - probably mini stereo
plug jacks don't
> they? Your speakers also have little mini stereo plugs that actually
plug into these
> jacks don't they? A normal human being with even minimal brain activity
would quickly
> realize that a couple of $.50 Y connectors from radio shack would soon
solve his
> problem...
> Of course, if you are the standard moron that owns a computer these
days, I would advise
> you to do all this fiddling around while the computer was powered on and
playing sounds
> very loudly! Hoping beyond hope that you would be standing in a puddle of
salt water
> while doing so, with one hand on the hot water pipe.... (just covering
all the bases
> here)
>
>

And just how is your simple "Y" adapter going to prevent sounds (electrical
signals) from being pumped into the INPUT of the other sound card?

Kanda' Jalen Eirsie wrote:
> Greetings...
>
> On Sat, 10 Apr 2004 12:50:59 +0100, "OrmesbyJohn" <> wrote:
>
>
>>I'm sure its a simple piece of kit but what do I need to be able to link one
>>set of speakers with two adjacent pc soundcards?
>>Thanks
>>
>
>
>
> Oh MY GOD!!!!
>
> Apparently they no longer teach simple problem solving anymore in liberal schools....
>
> How the hell did you ever find Usenet!???
>
> Just in case you are NOT a troll - I'll answer your stupid question before I continue to
> flame your incredible stupidity! No - I'll just save time and answer your stupid question
> WHILE continuing to flame your incredible stupidity...
>
>
> The back of your sound cards have plug in jacks - probably mini stereo plug jacks don't
> they? Your speakers also have little mini stereo plugs that actually plug into these
> jacks don't they? A normal human being with even minimal brain activity would quickly
> realize that a couple of $.50 Y connectors from radio shack would soon solve his
> problem...
> Of course, if you are the standard moron that owns a computer these days, I would advise
> you to do all this fiddling around while the computer was powered on and playing sounds
> very loudly! Hoping beyond hope that you would be standing in a puddle of salt water
> while doing so, with one hand on the hot water pipe.... (just covering all the bases
> here)
>
>
Oh what an absolutely great idea. Now it is such a good idea that I hope
that you try it yourself on your own sound cards. Even better, go out
and buy two very expensive new sound cards and try it with them.

After you have done that, perhaps you would also like to buy two ac
generators, nice expensive ones if you please, and use your nice Y cable
idea on that. Get them both running nicely and then plug a Y cable in.
Please take out lots of life assurance too, as your next of kin deserves
a break.

In short, you can use a Y cable to connect the INPUTS of two sound
cards. You can even use a Y cable to connect the INPUTS of two speakers
to one sound card. But if you use a Y cable to connect the outputs of
two sound cards to one set of speakers, both of the sound card will try
very hard to fry the other - until one or both succeeds.

It works OK with DC outputs of the same voltage. But the problem of
connecting AC outputs (like generators and sound cards) in parallel is
that, sooner or later, one is trying to drive the output positive whilst
the other is trying to drive it negative. Do try this with two nice big
truck batteries - firstly connect like terminals together, then
reverse the leads.

On Sun, 11 Apr 2004 15:07:01 -0700, "Toolman Tim"
<> wrote:
>
>"Kanda' Jalen Eirsie" <> wrote in message
>news:...
>> Greetings...
>>
>> On Sat, 10 Apr 2004 12:50:59 +0100, "OrmesbyJohn"
><> wrote:
>>
>> >I'm sure its a simple piece of kit but what do I need to be able to link
>one
>> >set of speakers with two adjacent pc soundcards?
>> >Thanks
>> >
>>
>>
>> Oh MY GOD!!!!
>>
>> Apparently they no longer teach simple problem solving anymore in
>liberal schools....
>>
>> How the hell did you ever find Usenet!???
>>
>> Just in case you are NOT a troll - I'll answer your stupid question
>before I continue to
>> flame your incredible stupidity! No - I'll just save time and answer your
>stupid question
>> WHILE continuing to flame your incredible stupidity...
>>
>>
>> The back of your sound cards have plug in jacks - probably mini stereo
>plug jacks don't
>> they? Your speakers also have little mini stereo plugs that actually
>plug into these
>> jacks don't they? A normal human being with even minimal brain activity
>would quickly
>> realize that a couple of $.50 Y connectors from radio shack would soon
>solve his
>> problem...
>> Of course, if you are the standard moron that owns a computer these
>days, I would advise
>> you to do all this fiddling around while the computer was powered on and
>playing sounds
>> very loudly! Hoping beyond hope that you would be standing in a puddle of
>salt water
>> while doing so, with one hand on the hot water pipe.... (just covering
>all the bases
>> here)
>>
>>
>
>And just how is your simple "Y" adapter going to prevent sounds (electrical
>signals) from being pumped into the INPUT of the other sound card?

Not that I am siding with this poster, but my first reply did mention
using a simple Y connector. My point was that the speakers connect to
the "output" and not the input.

On Sun, 11 Apr 2004 23:28:06 +0100, Palindr?me <>
wrote:
>Kanda' Jalen Eirsie wrote:
>
>> Greetings...
>>
>> On Sat, 10 Apr 2004 12:50:59 +0100, "OrmesbyJohn" <> wrote:
>>
>>
>>>I'm sure its a simple piece of kit but what do I need to be able to link one
>>>set of speakers with two adjacent pc soundcards?
>>>Thanks
>>>
>>
>>
>>
>> Oh MY GOD!!!!
>>
>> Apparently they no longer teach simple problem solving anymore in liberal schools....
>>
>> How the hell did you ever find Usenet!???
>>
>> Just in case you are NOT a troll - I'll answer your stupid question before I continue to
>> flame your incredible stupidity! No - I'll just save time and answer your stupid question
>> WHILE continuing to flame your incredible stupidity...
>>
>>
>> The back of your sound cards have plug in jacks - probably mini stereo plug jacks don't
>> they? Your speakers also have little mini stereo plugs that actually plug into these
>> jacks don't they? A normal human being with even minimal brain activity would quickly
>> realize that a couple of $.50 Y connectors from radio shack would soon solve his
>> problem...
>> Of course, if you are the standard moron that owns a computer these days, I would advise
>> you to do all this fiddling around while the computer was powered on and playing sounds
>> very loudly! Hoping beyond hope that you would be standing in a puddle of salt water
>> while doing so, with one hand on the hot water pipe.... (just covering all the bases
>> here)
>>
>>
>Oh what an absolutely great idea. Now it is such a good idea that I hope
>that you try it yourself on your own sound cards. Even better, go out
>and buy two very expensive new sound cards and try it with them.
>
>After you have done that, perhaps you would also like to buy two ac
>generators, nice expensive ones if you please, and use your nice Y cable
>idea on that. Get them both running nicely and then plug a Y cable in.
>Please take out lots of life assurance too, as your next of kin deserves
>a break.
>
>In short, you can use a Y cable to connect the INPUTS of two sound
>cards. You can even use a Y cable to connect the INPUTS of two speakers
>to one sound card. But if you use a Y cable to connect the outputs of
>two sound cards to one set of speakers, both of the sound card will try
>very hard to fry the other - until one or both succeeds.

Again I am not siding with the person you replied to here either, but
my original post mentioned using a simple Y connector.

I find a flaw in your allowing to Merge 2 sources into a single input
of the soundcard. There is a potential of overdriving the input
amplifier should both sources fire at the same time.

However, the speakers as output devices can tolerate the output of
multiple devices. You state that the 2 sound cards will try to fry
each other but the outputs should be gated to reject the signal coming
in from the other source, and the path of least resistance would be
the speakers.
>
>It works OK with DC outputs of the same voltage. But the problem of
>connecting AC outputs (like generators and sound cards) in parallel is
>that, sooner or later, one is trying to drive the output positive whilst
>the other is trying to drive it negative. Do try this with two nice big
> truck batteries - firstly connect like terminals together, then
>reverse the leads.
>

The opamps in the sound card, (or any analog device that I am aware of
anyway) work on DC current whereas the generators you mention would
work on AC current, and at a much larger push.

As far as connecting speakers in series or parallel, series is the
prefered choice, but this concerns connecting 2 speakers to a single
source and not dual source to a single speaker.

If we connect 2 - 8ohm speakers in series, then we create a resistance
of nearly 16 ohms, which is harmless but will substantially reduce the
output volume. If we connect them in paralell however, then we create
a resistance of nearly 4 ohms, which would not suppress the output
sufficiently and could actually suck the guts out of the opamp.

This explains the reason for adding a resistor from 1 lead of a
speaker to ground to split the load on the speaker which is really a
resistor anyway, whereas a capacitor is typically added in parallel to
the 2 leads, but more for sound shaping rather than load management.

On 4/11/2004 11:33:47 PM, Millimeter wrote:
>On Sun, 11 Apr 2004 23:28:06 +0100, Palindr?me <>
>wrote:
>
>>Kanda' Jalen Eirsie wrote:
>>
>>> Greetings...
>>>
>>> On Sat, 10 Apr 2004 12:50:59 +0100, "OrmesbyJohn" <> wrote:
>>>
>>>
>>>>I'm sure its a simple piece of kit but what do I need to be able to link one
>>>>set of speakers with two adjacent pc soundcards?
>>>>Thanks
>>>>
>>>
>>>
>>>
>>> Oh MY GOD!!!!
>>>
>>> Apparently they no longer teach simple problem solving anymore in liberal schools....
>>>
>>> How the hell did you ever find Usenet!???
>>>
>>> Just in case you are NOT a troll - I'll answer your stupid question before I continue to
>>> flame your incredible stupidity! No - I'll just save time and answer your stupid question
>>> WHILE continuing to flame your incredible stupidity...
>>>
>>>
>>> The back of your sound cards have plug in jacks - probably mini stereo plug jacks don't
>>> they? Your speakers also have little mini stereo plugs that actually plug into these
>>> jacks don't they? A normal human being with even minimal brain activity would quickly
>>> realize that a couple of $.50 Y connectors from radio shack would soon solve his
>>> problem...
>>> Of course, if you are the standard moron that owns a computer these days, I would advise
>>> you to do all this fiddling around while the computer was powered on and playing sounds
>>> very loudly! Hoping beyond hope that you would be standing in a puddle of salt water
>>> while doing so, with one hand on the hot water pipe.... (just covering all the bases
>>> here)
>>>
>>>
>>Oh what an absolutely great idea. Now it is such a good idea that I hope
>>that you try it yourself on your own sound cards. Even better, go out
>>and buy two very expensive new sound cards and try it with them.
>>
>>After you have done that, perhaps you would also like to buy two ac
>>generators, nice expensive ones if you please, and use your nice Y cable
>>idea on that. Get them both running nicely and then plug a Y cable in.
>>Please take out lots of life assurance too, as your next of kin deserves
>>a break.
>>
>>In short, you can use a Y cable to connect the INPUTS of two sound
>>cards. You can even use a Y cable to connect the INPUTS of two speakers
>>to one sound card. But if you use a Y cable to connect the outputs of
>>two sound cards to one set of speakers, both of the sound card will try
>>very hard to fry the other - until one or both succeeds.
>
>Again I am not siding with the person you replied to here either, but
>my original post mentioned using a simple Y connector.
>
>I find a flaw in your allowing to Merge 2 sources into a single input
>of the soundcard. There is a potential of overdriving the input
>amplifier should both sources fire at the same time.
>
>However, the speakers as output devices can tolerate the output of
>multiple devices. You state that the 2 sound cards will try to fry
>each other but the outputs should be gated to reject the signal coming
>in from the other source, and the path of least resistance would be
>the speakers.
>
>>
>>It works OK with DC outputs of the same voltage. But the problem of
>>connecting AC outputs (like generators and sound cards) in parallel is
>>that, sooner or later, one is trying to drive the output positive whilst
>>the other is trying to drive it negative. Do try this with two nice big
>> truck batteries - firstly connect like terminals together, then
>>reverse the leads.
>>
>
>The opamps in the sound card, (or any analog device that I am aware of
>anyway) work on DC current whereas the generators you mention would
>work on AC current, and at a much larger push.
>
>As far as connecting speakers in series or parallel, series is the
>prefered choice, but this concerns connecting 2 speakers to a single
>source and not dual source to a single speaker.
>
>If we connect 2 - 8ohm speakers in series, then we create a resistance
>of nearly 16 ohms, which is harmless but will substantially reduce the
>output volume. If we connect them in paralell however, then we create
>a resistance of nearly 4 ohms, which would not suppress the output
>sufficiently and could actually suck the guts out of the opamp.
>
>This explains the reason for adding a resistor from 1 lead of a
>speaker to ground to split the load on the speaker which is really a
>resistor anyway, whereas a capacitor is typically added in parallel to
>the 2 leads, but more for sound shaping rather than load management.
>
>Millimeter
>

Wow...Well Said......Outstanding reply........I taught electronics
for 10 years and could not have said it better......You are an "ace"!!!!

Millimeter wrote:
> On Sun, 11 Apr 2004 23:28:06 +0100, Palindr?me <>
> wrote:
>
>
>>Kanda' Jalen Eirsie wrote:
>>
>>
>>>Greetings...
>>>
>>>On Sat, 10 Apr 2004 12:50:59 +0100, "OrmesbyJohn" <> wrote:
>>>
>>>
>>>
>>>>I'm sure its a simple piece of kit but what do I need to be able to link one
>>>>set of speakers with two adjacent pc soundcards?
>>>>Thanks
>>>>
>>>
>>>
>>>
>>> Oh MY GOD!!!!
>>>
>>> Apparently they no longer teach simple problem solving anymore in liberal schools....
>>>
>>> How the hell did you ever find Usenet!???
>>>
>>> Just in case you are NOT a troll - I'll answer your stupid question before I continue to
>>>flame your incredible stupidity! No - I'll just save time and answer your stupid question
>>>WHILE continuing to flame your incredible stupidity...
>>>
>>>
>>> The back of your sound cards have plug in jacks - probably mini stereo plug jacks don't
>>>they? Your speakers also have little mini stereo plugs that actually plug into these
>>>jacks don't they? A normal human being with even minimal brain activity would quickly
>>>realize that a couple of $.50 Y connectors from radio shack would soon solve his
>>>problem...
>>> Of course, if you are the standard moron that owns a computer these days, I would advise
>>>you to do all this fiddling around while the computer was powered on and playing sounds
>>>very loudly! Hoping beyond hope that you would be standing in a puddle of salt water
>>>while doing so, with one hand on the hot water pipe.... (just covering all the bases
>>>here)
>>>
>>>
>>
>>Oh what an absolutely great idea. Now it is such a good idea that I hope
>>that you try it yourself on your own sound cards. Even better, go out
>>and buy two very expensive new sound cards and try it with them.
>>
>>After you have done that, perhaps you would also like to buy two ac
>>generators, nice expensive ones if you please, and use your nice Y cable
>>idea on that. Get them both running nicely and then plug a Y cable in.
>>Please take out lots of life assurance too, as your next of kin deserves
>>a break.
>>
>>In short, you can use a Y cable to connect the INPUTS of two sound
>>cards. You can even use a Y cable to connect the INPUTS of two speakers
>>to one sound card. But if you use a Y cable to connect the outputs of
>>two sound cards to one set of speakers, both of the sound card will try
>>very hard to fry the other - until one or both succeeds.
>
>
> Again I am not siding with the person you replied to here either, but
> my original post mentioned using a simple Y connector.
>
> I find a flaw in your allowing to Merge 2 sources into a single input
> of the soundcard. There is a potential of overdriving the input
> amplifier should both sources fire at the same time.

No flaw. The input to a sound card won't be overdriven because it is
high impedance and the signals are being applied in parallel, not
series. The only thing that may be overdriven is the OUTPUTS of the two
systems providing the signals. They must be high impedance too.
>
> However, the speakers as output devices can tolerate the output of
> multiple devices. You state that the 2 sound cards will try to fry
> each other but the outputs should be gated to reject the signal coming
> in from the other source, and the path of least resistance would be
> the speakers.
Not true. "Speakers" aren't just speakers. They are combined amplifiers
with speakers. The amplifiers have high impedance INPUTS - much higher
than the low impedance outputs of the sound cards. If you connext a
sound card direct to unpowered speakers, the sound output would be
minimal. (Inevitably there are exceptions, a very small number of sound
cards do include power amplifiers with enough output to drive unpowered
speakers).
>
>
>>It works OK with DC outputs of the same voltage. But the problem of
>>connecting AC outputs (like generators and sound cards) in parallel is
>>that, sooner or later, one is trying to drive the output positive whilst
>>the other is trying to drive it negative. Do try this with two nice big
>> truck batteries - firstly connect like terminals together, then
>>reverse the leads.
>>
>
>
> The opamps in the sound card, (or any analog device that I am aware of
> anyway) work on DC current whereas the generators you mention would
> work on AC current, and at a much larger push.

Nope, amplifiers in sound cards work on ac signals (in a range of
frequencies from 20Hz to 20kHz, typically). They are there to amplify
audio signals. Of course they take power from the dc power rails. The
amplifiers used may be opamps, but they are preceded by filters which
will stop them having a dc SIGNAL input. You can use opamps in control
circuitry where they do have DC inputs, say as voltage regulators, but
an audio amplifier specifically excludes DC inputs. Otherwise the output
would be biased towards one supply rail or the other and thus an imposed
ac signal (the audio signal we are interested in) would be clipped
prematurely as it rose in that direction.
>
> As far as connecting speakers in series or parallel, series is the
> prefered choice, but this concerns connecting 2 speakers to a single
> source and not dual source to a single speaker.

This is true for unpowered speakers. Sound cards are seldom connected
directly to unpowered speakers, but to the INPUTS of power amplifiers -
oftern built into the speaker cases and powered by an external mains lead.
>
> If we connect 2 - 8ohm speakers in series, then we create a resistance
> of nearly 16 ohms, which is harmless but will substantially reduce the
> output volume. If we connect them in paralell however, then we create
> a resistance of nearly 4 ohms, which would not suppress the output
> sufficiently and could actually suck the guts out of the opamp.

True but irrelevant as we are not considering the low impedance speakers
but the high impedance inputs to the amplifiers contained within powered
speakers.
>
> This explains the reason for adding a resistor from 1 lead of a
> speaker to ground to split the load on the speaker which is really a
> resistor anyway, whereas a capacitor is typically added in parallel to
> the 2 leads, but more for sound shaping rather than load management.

Yep. Iy you parallel two unpowered speakers, you halve the impedance
presented to the amplifier. So if they are 8 ohm speakers, when
paralleled the combination presents an impedance of 4 ohms. So you can
add a 4 ohm resistor in series to bring the load back up to 8 ohms
again. But the OP wasn't asking about paralleling speakers, he was
asking about paralleling sound card outputs.

Putting a capacitor directly across a speaker, i.e. right across the
output of an amplifier, is not a good idea. At high enough signal
frequencies the capacitor will act as a short circuit and overload the
amplifier. The usual way a capacitor is used across a speaker is in
series with a tweeter, as part of the cross over network distributing
the correct range of frequencies to the relevant output devices.

The output impedance of an amplifier is typically very low. If you
connect two outputs together in parallel it IS like paralleling the
output of two mains generators - which also have very low output
impedances. Worse in some respects in that, at least the mains
generators are producing the same nominal voltage and frequency. It is
possible to parallel single frequency, single voltage generators -
otherwise the National Grid wouldn't work. However, the outputs from two
amplifiers are at a whole range of frequencies and signal levels and
directly paralleling them will be catastrophic. Each would try to pull
the output to its level and massive currents would flow in the process.

You must never use a Y cable to directly connect the outputs of two
amplifiers together to a single load, unless they have been designed to
do so or unless you have added resistors in series with the outputs to
limit the resulting currents.

On Mon, 12 Apr 2004 12:02:11 +0100, Palindr?me <>
wrote:
>Millimeter wrote:
>> On Sun, 11 Apr 2004 23:28:06 +0100, Palindr?me <>
>> wrote:
>>
>>
>>>Kanda' Jalen Eirsie wrote:
>>>
>>>
>>>>Greetings...
>>>>
>>>>On Sat, 10 Apr 2004 12:50:59 +0100, "OrmesbyJohn" <> wrote:
>>>>
>>>>
>>>>
>>>>>I'm sure its a simple piece of kit but what do I need to be able to link one
>>>>>set of speakers with two adjacent pc soundcards?
>>>>>Thanks
>>>>>
>>>>
>>>>
>>>>
>>>> Oh MY GOD!!!!
>>>>
>>>> Apparently they no longer teach simple problem solving anymore in liberal schools....
>>>>
>>>> How the hell did you ever find Usenet!???
>>>>
>>>> Just in case you are NOT a troll - I'll answer your stupid question before I continue to
>>>>flame your incredible stupidity! No - I'll just save time and answer your stupid question
>>>>WHILE continuing to flame your incredible stupidity...
>>>>
>>>>
>>>> The back of your sound cards have plug in jacks - probably mini stereo plug jacks don't
>>>>they? Your speakers also have little mini stereo plugs that actually plug into these
>>>>jacks don't they? A normal human being with even minimal brain activity would quickly
>>>>realize that a couple of $.50 Y connectors from radio shack would soon solve his
>>>>problem...
>>>> Of course, if you are the standard moron that owns a computer these days, I would advise
>>>>you to do all this fiddling around while the computer was powered on and playing sounds
>>>>very loudly! Hoping beyond hope that you would be standing in a puddle of salt water
>>>>while doing so, with one hand on the hot water pipe.... (just covering all the bases
>>>>here)
>>>>
>>>>
>>>
>>>Oh what an absolutely great idea. Now it is such a good idea that I hope
>>>that you try it yourself on your own sound cards. Even better, go out
>>>and buy two very expensive new sound cards and try it with them.
>>>
>>>After you have done that, perhaps you would also like to buy two ac
>>>generators, nice expensive ones if you please, and use your nice Y cable
>>>idea on that. Get them both running nicely and then plug a Y cable in.
>>>Please take out lots of life assurance too, as your next of kin deserves
>>>a break.
>>>
>>>In short, you can use a Y cable to connect the INPUTS of two sound
>>>cards. You can even use a Y cable to connect the INPUTS of two speakers
>>>to one sound card. But if you use a Y cable to connect the outputs of
>>>two sound cards to one set of speakers, both of the sound card will try
>>>very hard to fry the other - until one or both succeeds.
>>
>>
>> Again I am not siding with the person you replied to here either, but
>> my original post mentioned using a simple Y connector.
>>
>> I find a flaw in your allowing to Merge 2 sources into a single input
>> of the soundcard. There is a potential of overdriving the input
>> amplifier should both sources fire at the same time.
>
>No flaw. The input to a sound card won't be overdriven because it is
>high impedance and the signals are being applied in parallel, not
>series. The only thing that may be overdriven is the OUTPUTS of the two
>systems providing the signals. They must be high impedance too.
>
>>
>> However, the speakers as output devices can tolerate the output of
>> multiple devices. You state that the 2 sound cards will try to fry
>> each other but the outputs should be gated to reject the signal coming
>> in from the other source, and the path of least resistance would be
>> the speakers.
>Not true. "Speakers" aren't just speakers. They are combined amplifiers
>with speakers. The amplifiers have high impedance INPUTS - much higher
>than the low impedance outputs of the sound cards. If you connext a
>sound card direct to unpowered speakers, the sound output would be
>minimal. (Inevitably there are exceptions, a very small number of sound
>cards do include power amplifiers with enough output to drive unpowered
>speakers).
>>
>>
>>>It works OK with DC outputs of the same voltage. But the problem of
>>>connecting AC outputs (like generators and sound cards) in parallel is
>>>that, sooner or later, one is trying to drive the output positive whilst
>>>the other is trying to drive it negative. Do try this with two nice big
>>> truck batteries - firstly connect like terminals together, then
>>>reverse the leads.
>>>

No offence intended but lets sort out some misconceptions here.

1. We are talking about the output ports from the soundcard, not the
inputs to the sound card.

2. If you push AC power through an opamp, it will cook before a full
cycle has completed. They are gated to accept signals in a single
direction not both.

>>
>>
>> The opamps in the sound card, (or any analog device that I am aware of
>> anyway) work on DC current whereas the generators you mention would
>> work on AC current, and at a much larger push.
>
>Nope, amplifiers in sound cards work on ac signals (in a range of
>frequencies from 20Hz to 20kHz, typically). They are there to amplify

You seem to be muddling several points into a single explanation here.
1. The sound amplification on a sound card happens within an IC which
is powered by DC current, and works on DC signals.

The input and output pins for both the power circuit and the
amplification circuit are labled (at least in the IC schematic) as
being either positive or negative. If you reverse them, you cook the
chip. If you use AC, then you would cook the chip during the first
cycle.

2. Hz/KHz do not refer to current but rather the waveform of the tone.
The range you mention would envelope the sounds we are capable of
hearing, from lowest to highest in pitch.
>audio signals. Of course they take power from the dc power rails. The
>amplifiers used may be opamps, but they are preceded by filters which
>will stop them having a dc SIGNAL input. You can use opamps in control
>circuitry where they do have DC inputs, say as voltage regulators, but
>an audio amplifier specifically excludes DC inputs. Otherwise the output
>would be biased towards one supply rail or the other and thus an imposed
> ac signal (the audio signal we are interested in) would be clipped
>prematurely as it rose in that direction.

Nope. The power rails may provide the power to the opamp, but the
signal path is a seperate circuit all together. Both the power and
the signal path use DC. The filter you are speaking about filters off
DC-offsets and not DC altogether.

What this means is that if the average signal strength is 2 vdc, there
may be some fluctuations toward 3 vdc and 1vdc. The farther the
deviation, the higher the rate of sound degradation. By filtering off
the DC-offset, there can be some measure of control over sound
degradation.

In AC we have 2 wires for single phase applications. 1 is at or near
ground potential, and the other alternates. Assuming a voltage level
of 5 volts, the first half of the cycle the hot wire is starting at -5
volts and rising toward +5 volts. The second half of the cycle it
falls from +5 to -5.

In DC we have 2 wires also. 1 is at or near ground potential, the
other only rises to +5 then falls to 0, there is no inverse cycle
towards -5. As you know that in computers, bits are determined to be
set if the voltage is hi, and not set if low. So anything below 0 is
counted as not set, where anything above the threshold (i.e. +1 to +3
volts) is counted as hi or set.

A simple tes would be to hook your volt meter to the 2 pins on an
unpowered microphone. When you speak into the microphone you will
notice the meter reacting as I suggested fo DC circuits above, and not
for AC. A powered microphone simply amplifies the signal to above
line level but we are only talking millivolts here, not hundreds of
volts.
>>
>> As far as connecting speakers in series or parallel, series is the
>> prefered choice, but this concerns connecting 2 speakers to a single
>> source and not dual source to a single speaker.

What's the difference here? 1 source or 10, the speaker still has a
resistor that bleeds of excess current to ground to prevent
overloading.
>
>This is true for unpowered speakers. Sound cards are seldom connected
>directly to unpowered speakers, but to the INPUTS of power amplifiers -
>oftern built into the speaker cases and powered by an external mains lead.

Uhhm, I think you are confusing speakers and speaker boxes here.
A powered speaker is nothing more than a speaker with an amplifier
added in to increase volume. Powered speakers allow you to use
line-level outputs from the soundcard rather than normal outputs so
you can use your own amplification and tone shaping circuitry.
>>
>> If we connect 2 - 8ohm speakers in series, then we create a resistance
>> of nearly 16 ohms, which is harmless but will substantially reduce the
>> output volume. If we connect them in paralell however, then we create
>> a resistance of nearly 4 ohms, which would not suppress the output
>> sufficiently and could actually suck the guts out of the opamp.
>
>True but irrelevant as we are not considering the low impedance speakers
>but the high impedance inputs to the amplifiers contained within powered
>speakers.
>

IMHO, we were trying to discover if the output of one soundcard could
enter through the output of a second soundcard, by virtue of the fact
that they both output to a common device, being the single speaker.
>>
>> This explains the reason for adding a resistor from 1 lead of a
>> speaker to ground to split the load on the speaker which is really a
>> resistor anyway, whereas a capacitor is typically added in parallel to
>> the 2 leads, but more for sound shaping rather than load management.
>
>Yep. Iy you parallel two unpowered speakers, you halve the impedance
>presented to the amplifier. So if they are 8 ohm speakers, when
>paralleled the combination presents an impedance of 4 ohms. So you can
>add a 4 ohm resistor in series to bring the load back up to 8 ohms
>again. But the OP wasn't asking about paralleling speakers, he was
>asking about paralleling sound card outputs.

Actually you would have to add 8ohm resistor but that's twiddling
bits. The speakers would still be at 8 ohms whether you had 1, 2,
or 10 sources at 2-3 vdc.
>
>Putting a capacitor directly across a speaker, i.e. right across the
>output of an amplifier, is not a good idea. At high enough signal
>frequencies the capacitor will act as a short circuit and overload the
>amplifier. The usual way a capacitor is used across a speaker is in
>series with a tweeter, as part of the cross over network distributing
>the correct range of frequencies to the relevant output devices.

Nearly right, but compare this to a guitar amplifier/speaker
combination where there is no tweeter or woofer. The effect of the
capacitor would be to bleed the high signals to ground, rather than a
tweeter. Using a resistor in combination with the capacitor allows
you to better isolate which frequencies will not be excluded.
>
>The output impedance of an amplifier is typically very low. If you
>connect two outputs together in parallel it IS like paralleling the
>output of two mains generators - which also have very low output
>impedances. Worse in some respects in that, at least the mains
>generators are producing the same nominal voltage and frequency. It is
>possible to parallel single frequency, single voltage generators -
>otherwise the National Grid wouldn't work. However, the outputs from two
>amplifiers are at a whole range of frequencies and signal levels and
>directly paralleling them will be catastrophic. Each would try to pull
>the output to its level and massive currents would flow in the process.

Again, if you are working in AC current then the cycles would have to
occur at the same timing and resolution to avoid collision, ie if one
source is in the hi side of the cycle while the second source is in
the low side.
Sound cards work with DC signals which couldn't collide because there
is no low side to the cycle.
>
>You must never use a Y cable to directly connect the outputs of two
>amplifiers together to a single load, unless they have been designed to
>do so or unless you have added resistors in series with the outputs to
>limit the resulting currents.

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